Tonometer



FIG. 1 is a top plan view of a tonometer showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a left side view thereof; and

FIG. 6 is a bottom plan view thereof.

The ornamental design for a tonometer, as shown.